Multiunit radio receiving system



Nov. 7, 1939. R. KIMBALL MULTIUNIT RADIO RECEIVING SYSTEM Filed July 3,1937 4 Sheets-Sheet 1 Nov. 7, 1939. R. KIMBALL MULTIUNIT RADIO RECEIVINGSYSTEM Filed July 3, 1957 4 Sheets-Sheet 2 w haw Nov. 7, 1939. R.KIMBALL MULTIUNI'I RADIO RECEIVING SYSTEM Filed July 3, 1937 4Sheets-Sheet 5 Nov. 7, 1939.

' R. KIMBALL MULTIUNIT RADIO RECEIVING SYSTEM Filed July 3, 1937 4Sheets-Sheet 4 b w r 35 mt T SQ 3 F352.

p IB N Patented Nov. 7, 1939 warren stares PATENT OFFEQE MULTIUNIT,RADIO RECEIVING SYSTEM Raymond Kimball, Hollywood, Calif.

Application July 3, 1937, Serial No. 151,897

19 Claims.

This invention is a radio receiving system pro viding for selectivelycontrolled intercommunication among a plurality of inter-relatedstations.

One of the objects of the invention is to provide a system of thecharacter mentioned characterized by a plurality of inter-related radioreceiving stations and means selectively controllable at each of saidstations for establishing oral communication with any one of the otherstations. A further object is to provide simple means for temporarilyconverting the sound reproducing element of any station into amicrophone and placing it into communication with the sound reproducingelement of any other station of the system. A further object is toprovide means at each station for selectively effecting temporaryinterruption of radio reception at any of the other stations of thesystem.

The invention will be hereinafter fully set forth and particularlypointed out in the claims.

In the accompanying drawings,

Figures 1, 2, 3 and 4 are diagrammatic views of a corresponding numberof portions of the radio receiving system, it being understood that allof them are part of a single lay-out and should be regarded as assembledin joint relation as one larger complete plan, with Figure 2 at theright of Figure 1 and Figures 3 and 4 below Figures 1 and 2respectively.

Referring to the drawings, A diagrammatically illustrates a programpower-supply-contrcl device of the type provided with means controllablefrom a distance for making and breaking the circuit to the varioustuners and amplifiers of the system. B indicates an intercommunicatingpower supply device having means controllable from a distance forestablishing intercommunication between control stations. C representsan amplifier controllable from a distance for amplifyingintercommunication between stations. D is a transformer for reducing theusual 110 volt power current to a 6 volt power supply.

Any number of stations may be employed, each with its duplicated controldevices and loud speaker, four of such stations, located in separaterooms, being shown for purposes of illustration. The several stationsare represented by panel boards CP CP (3P and 3 respectively, eachprovided with circuit closing devices and wiring, all to be described indetail later. The circuits and method of control are identical in eachinstance, except that the circuit closing devices carried by panelboards CP and CP are illustrated as of the push button type and those ofpanel boards CP and CP are of the rotatable gang switch type. The panelboards may be of the portable type or of the fixed wall type, the pushbutton controls being preferably used with the portable type CP and (JPand the gang switch being preferably carried by the fixed wall type CPand GP.

The main lead-in wire a is connected by a branch wire 28 to the programpower supply A, by a branch wire 2!, to the intercommunicating powersupply B by wire M and is also directly connected with the transformerD. Leading from the intercommunicating power supply B is a wire 22 towhich is connected the fixed contact rv of each of'a series of relays#lil, #ll, #l2 and #13 respectively. Leading from the program powersupply is a wire 23v which by means of a wire 24 is connected to thefixed contact 1 of each .of relays #M, #i and #lfi. Each relay #14 and#l5is provided with two sets of contacts, namely one set consisting of afixed contact 1' and a movablecontact s, and the other set consisting ofa fixed contact 0 and a movable contact o. The two movable contacts areso connected as to move together. All of said relays #ll), #H, #l2, #l3,#l4, #l5, and #IG have their movable contacts 8 suitably connected witha return wire 25, which in turn isconnected by a wire 26 to the mainreturn wire b. Contact 0' of each relay id and #I5 is connected with thewire 28. Contact 0' of relay #14 is connected with Wire I28 by Wire 123and contact 0' of relay #I5 is connected to wire l2? by wire 38.

Each of the coils of the respective relays #lll, -#ll, #l2, #l3, #l4,#IE has one terminal connected with a common feed wire 28, which in turnis connected to the output side of transformer D, by wire 29. Thecircuit connections with the other terminals of said coils will bedescribed later in connection with the detail description of therespective control stations.-

The intercommunicating power supply B is so constructed that the circuitto wire 2N and its connections is normally broken, said circuit beingclosed, however, upon the actuation of any one of the relays #10, #l l,#IE and #53. It will be observed that the fixed contact r of each ofthese relays. is connected with the wire 22 and that the movable contact3 of each relay is connected with the return wires 25 and 26.

In addition to the relays above described there is another group ofrelays arranged in pairs, to wit, #1 and #2, #3 and #d, #5 and #6, and#1 and #8, each having two fixed contacts, 8,, s and a movable contact 5The fixed contact s of each relay #I, #3, #5 and #1 is connected to acommon wire 28 Each fixed contact 8 of relays #I, #3, #5 and #1 isconnected with the movable contact 8 of relays #2, l, #6, #8,respectively. Each fixed contact s of relays #2, #4, #6, #8, isconnected to a common Wire 28 The movable contacts s of each relay #I,#3, #5 and #1 is connected with a wire I06 leading to a loud speaker,one for each control station, relay #1! being connected with LS ofcontrol panel CP', relay #3 with LS of P relay with LS of CP and relay#1 with LS of GP. Each loud speaker is also connected by wire I01 withwire 39. The fixed terminal .9 of relay #2 is connected with amplifierAM by wires I03 and IUS I04, s of relay #4 is connected with amplifierAM by wires I08, I09, II 0, s of relay #6 is connected directly withamplifier AM by wire H2, and s of relay #8 is directly connected withamplifier AM by wire H2 and H4.

One end of the coil of relay #I is connected to a terminal of the coilof relay #II], by means of a wire 38, said last-mentioned wire beingalso connected with conductor I I8. In a similar manner a terminal ofcoil of relay #3 is connected to a terminal of the coil of relay #II bymeans of wire 3|, said wire also being connected with conductor I25, aterminal of the coil of relay #5 is connected with a terminal of thecoil of relay #I2 by wire 32 which wire is also connected with conductorI25; and a terminal of the coil of relay #1 is connected with a terminalof the coil of relay #I3 by a wire I23 which wire is also connected withconductor I21. Each of the other terminals of the coils of relays #III,#I I, #I 2 and #I3, as before stated are connected with the transformerwire 29 by wire 28.

One terminal of the coil of relay #2 is connected with conductor II1 bya wire H1 one terminal of the coil of relay #4 is connected withconductor H9 by a wire B one terminal of the coil of relay #6 isconnected with conductor I22 by a wire I22 and one terminal of the coilof relay #8 is connected with a conductor I23 by a wire I23 The portablecontrol panel CP is provided with a plurality of diagrammaticallyillustrated switches P P, P P P P P P P P P P preferably in the form ofpush buttons. Push button P which is the on-oil button, has one terminal11 connected to a terminal of the coil of relay l5 by means ofconductors 35, 36 and 31 the other terminal of said coil being connectedwith the ground wire 28. The movable contact 0 of relay I5 is connectedto a pilot light L by means of wire 38, I21, 40, said light beinggrounded by wire AI in any suitable manner. Thus, the pilot light isilluminated when the relay I5 is in one position.

Relay #I5 is the on-off power supply for CP. It is of the pulsatingtype, operating one way on the first impulse and returning to its normalposition on the second impulse. The construction of the relay is suchthat the life of the pulsation is not a factor in the operation of thesystem.

Any number of radio tuners and amplifiers may be employed but forpurposes of illustration four tuners RT, RT RT, and RT*, and aphonograph amplifier one for each control panel, and four individualstation amplifiers AM, AM AM and AM are shown.

Located at a convenient position is relay #9 one terminal of the coilthereof being connected with wire 28 by wire 21*, the other terminalbeing connected with wire H6 by wire 6*. This relay is provided with twosets of contacts t, t, t and u, u u Contacts 25, t, u and u are fixedand contacts t and u are movable and so connected as to operate inunison. Fixed contacts t and u are connected by wire '6 with the inputof intercommunicatii g amplifier C. The input of amplifier C is alsoconnected with wire 39 by a wire ".5 Fixed contacts I" and u areconnected by means of a wire 1%, to the output of amplifier C. Theoutput of amplifier C is also connected with wire 39" by wire 21. Themovable contact u is connected by wire 25 with wires 28 and movablecontact t is connected by a wire u with Wire 28*.

The radio tuners and amplifiers all receive their operating voltagesfrom the common program power supply A by means of wire 45 leading fromthe latter, and having a branch wire 46 connected with amplifier AM therespective amplifiers AM AM and AM also being connected by wires 41, 48and 49 respectively. Supply wire is also connected with a branch wire 50leading to radio tuners numbered RT and RT respectively, radio tuner RTbeing connected with the phonograph amplifier AM by means of a wire 5|.Tuners RT RT RT and RT are connected by suitable wires 52, 53 and 54respectively Leading from the antennae ANT is a wire 55 which isconnected by branch wires 56 with the respective tuners as shown. Eachof the radio tuners is provided with circuit wires (1, d respectively,said circuit wires of tuner RT being connected with line wires 60, 6Irespectively, the circuit wires d, d of tuner RT being connected withwires 52 and 63, wires 11', d of RT being connected with wires 54, 55,wires d d of RT being connected with wires 56, S1 and wires (1, d of RTbeing connected with wires 68, 69. The phonograph amplifier AM isconnected by branch wires d (1 with the wires 10 and 1| and is alsoconnected by suitable circuit wires 12 with the phonograph pick-up F.Wires 12, 13, 14 and 15 are dead wires and are only to be used in theevent that it is desired to increase the number of tuners.

Leading from the wire a is a branch wire 16 which is connected to oneside of the phonograph motor G, the other side of said motor beingconnected by means of a wire 11 to contact s of the relay #I'I. Theother contact 1' of relay I1 is connected through the wires 21 and 26 tothe wire 12.

Assuming that it is desired to tune in on any desired program at stationCP, the on-01f button P is depressed, thereby closing the circuit fromtransformer D via wire 29, wire 28, coil of relay #I5, wires 31, 36 and35, contacts p, p of switch P wires 38 39 and 46 to transformer D. Asthe coil of relay #I5 is energized contacts r and s of said relay arebrought into engagement, thereby closing a circuit from main inputconductor a, wire 20, program power supply A, wire 23, contacts r, s ofrelay #I5 and return through wires 21 and 26 to return wire b. Operationof relay #I5 also closes a circuit from transformer D, through wires 29,28, contacts 0, o of relay #I5, Wires 38 and 4!], pilot light L, wires4!, II to ground.

Current passing through program power supply A by reason of closing ofthe circuit through relay #I5 connects the main power line a with wire45 in a manner well understood in the art.

Any one of the five program selector buttons,

wardlyfor selection of a radio and button P" is pressed downwardly forselection of phonograph program. Each of said program selector switcheshas four contacts as, :c, x and m respectively, connected to the outputof its corresponding radio tuner or the phonograph. The contact 3: ofbutton P is connected with the wire 6 I by means of a wire 89 and thecontact a: of that switch is connected with the wire 69 by means of awire M. In a similar manner, the contacts: of each of the switches P P PP, P are respectively connected by wires 82, 88, 89, 86 and 90 with therespective wires, 62, 64, 66, i3 and 68 and the contacts x of saidswitches are connected with the wires 63, 65, 51, H, 69, respectivelybywires 87, 83, '84, 9! and 85, respectively, thereby placing tuner R'Iunder the control of switch P the tuner RT under the control of switch P,the tuner RT under the control of switch P the tuner RT under thecontrol of switch P the tuner RT under the control of switch P and thephonograph amplifier under the control of switch P With the buttons ofthe program seiector switches in the top or open circuit positions,dummp load resistors R are arranged across the respective tuner orphonograph output circuits. Each resistor is equal to the inputimpedance of the room amplifier. When any program selector button isdepressed, the dummy load resistor of that particular switch isdisconnected from the tuner circuit and the output of the programchannel is connected through to the volume control VC Contact 3: of eachbutton is connected with the volume control by wire 39 and contact r isconnected to ground by wire ll One side of the volume control V0 isconnected by wire it!!! to amplifier AM the other wire llll from saidamplifier being grounded through the ground wire 4 I. In the case of thestation CP the output line is to the amplifier AM as stated. In asimilar manner amplifier AM is connected with the portable station CPand the amplifiers AM? and AM are respectively connectedin a similar wayto the respective stations CP and CP.

One side of the'output of each amplifier AM AM AM and AM is connected bymeans of a wire 92 with the common ground wire 39. The other-side of theoutput of amplifier AM is connected by means of wires S93, H13 and W4 tocontact s of relay #2.

While relays #l and #2 are in normal or off position the circuit will bethrough contacts s', s of relay #2, wire I95, contacts 5', s of relay#l, and wire I96 to speaker LS, and return by wire I01 which isconnected to the ground Wire 39. The other side of amplifier AM isconnected by wires H38, H33 and H9, relays #4 and #3 which in the ofiposition of the relays connects with the speaker LS through its wireHit, the return wire In! of said speaker being connected to ground wire39. In a similar manner, the terminals of relays #5 and #6 are placed incircuit with LS bywires H2, 105*, E96, l3! and 39; and the terminals ofrelays #l and #8 are placed in circuit with SP by wires 2 i95, lllii,l9? and 39. Each pair of relays #l and #2, #3 and #4, #5 and #6, and #1and #9 are intercommunicating relays and have no bearing on the programreproduction other than to cut it off when the intercommunica- 'tionsystem is being used.

The portable control 0P has an interlocking device I on allintercommunication selector buttons P P P P and all program selectorbuttons P", P P P P and P This interlocking device is so arranged in amanner well understood in the art, that when any of the above mentionedbuttons is depressed, it will be locked down until another button isdepressed, whereupon the first button is released and the second buttonlocks down. Devices of this type are very common and 5 it is notconsidered necessary to illustrate this type of device in detail. Thetwo topmost buttons P and P of the i2 button control are disconnectedfrom the interlocking device so that they do not lock down whiledepressed. I Each control station in the form of the inventionillustratedis provided with '12 circuit closers. For instance, oncontrol board OP twelve push buttons are shown, the button P being thepress-to-talk button which functions to reverse 15 the input and outputof the inter-communication amplifier by the operation of relay #9,setting up the calling speaker and the speaker whichis being calledalternately as microphone and reproducer. which is pressed to initiateor terminate the radio reception and to start or stop the normal radioreception functions. of the system. Buttons P P P and P are the callingor selector buttons for u the inter-communication system, one for each 5station on the system, P being out of use. By means of these buttons,the loud speakers at the respective stations may be selectivelydisconnected from the various amplifiers. For instance, the

button P controls the amplifier AM for loud BO speaker LS button Pcontrols amplifier AM for loud speaker LS button P controls theamplifier AM for loud speaker LS button P is an extra intercommunicationselector button and would normally be unconnected as shown or connected35 to an extra station. The button 2 controls the phonograph motorthrough relays-ll as follows: Depression of said button closes a circuitfrom transformer D, wires 29, 28, ll coil of relay #ll,

wires E22, IZI, Il contacts l'l l'i' .wires l'l 40 and 4 ii to ground.By energizing the coil of relay #ll circuit is closed by contacts 7, sof said relay through wires '36, phonograph motor G, wires 11, 27, 26and b.

Upon the depression of the button P, circuit is 45 closed from thetransformer D through the wires 29, 28, 21 and the coil of relay #9,wires l W21 l6, 6 the contacts of P, and wires tile, 39, 4!),- back totransformer D. Thus, the coil of relay #9 is energized so that themovable members 5 and a of said relay are shifted in such a manner as toreverse the connections of the" sound reproducer LS, and which ever ofthe reproducers I (LS LS or LS may be in the circuit due to selection bydepressed buttons P P or P, from 55 the input to the output of theinter-communication amplifier. f

Assuming that a person in the room where control panel CP' is located isdesirous of communicating with the person in the room where 60 'controlpanel CP is located, he will first depress the calling button P which isthe proper button to reach station'CP Depressing of the button P willclose a circuit from transformer D via wires 29, 28, coil of relay #IO,wires 30, H8, IN, '65

15h, 'l5l contacts o and o of button. P and return to transformer D bywires 49 39, and

- lll "The energizing of relay #ll! closes a circuit through theintercommunication'power supply B so that power is furnished to theinter- 7o communication elements of the system. Simultaneously, acircuit is also established from transformer D via wire 29, coil ofrelay #6, wire l22 contacts 2:, o of button P and wires 'IEI 40 39 and40 to the transformer.

The push button P is the on-off button #20 At the same 7 5 time anothercircuit is established from the transformer D via wires 29,. 28 and 21coil-of relay #l, wires-30, H8, IEI, l5l contacts 12 o of button P andwires IEI 40 39, 40 to D. It will be observed that when the coil ofrelay #6 is energized the movable contact s is moved out of engagementwith the fixed contact a and engages the contact 8, thereby cutting outthe amplifier AM The energizing of the coil of relay #l shifts themovable contact 5 of that relay out of engagement with contact s therebybreaking the circuit at these contacts and bringing contacts 8 and 3into engagement, thereby breaking the normal circuit to loud speaker LSand so connecting the latter with the intercommunicating amplifier Cthat the connections to the loud speaker LS must pass through thecontacts of relay #9. The circuit will now be from theintercommunicating amplifier C through wires 2%, u, W, 28 27*, contacts.9 and s of relay #2 and to loud speaker LS through wire I05, relay #Ito wire I06. At the same time circuit is established by relay #9 throughwires 15 contacts t, F, wires 14 28*, H 3, contacts 8, S of relay #5 andwire I06 to loud speaker LS on control panel CP By the foregoingchanges, loud speaker LS is now made to function as a'reproducer andloud speaker LS is functioning as a microphone, so that the person atcontrol board CP is listening in to the room in which loud speaker LS islocated, i. e. at control board CP Relay #9 normally functions toreverse the speakers which may have been placed in circuit therewithfrom the input to the output of the intercommunication amplifier C.Before the person at control board CP may talk and be heard through theloud speaker LS he must first press the pressto-talk button P on hiscontrol panel CP'. Normally, the circuits through the relay #9 areconnected with the output of the intercommunication amplifier C.Energizing of the coil of relay #9 shifts the movable contacts 15 and uso as to connect the speakers with the input and output of theintercommunication amplifier in the reverse order of the normal circuitsabove described. A conversation may then be carried on by the originatorof the call pressing the but ton P while talking, and releasing itwhile-listening. It will, of course, be understood that through theoperation of the relays #l and #6 as just described, the programs, ifany, which are being produced through speakers LS and LS are completelyout off while the conversation takes place, and that when theintercommunication selector switch P is returned to normal position theprograms originally being produced at both stations are replaced.

The arrangement of the circuits is such that any person at any one ofthe stations 0P, 0P, 0P CP may selectively communicate with any one ofthe other stations of the group by merely depressing the proper buttonP, P or P as the case may be, and operating the button P as abovedescribed. For instance, by depressing the button P the coils of relays#i, #l', #8 and #I3 are energized so as to close the circuit throughintercommunicating power supply B, to cut out amplifier AM*, and toplace speakers LS and LS in communication. The power circuit is closedby relay !3, and the amplifier AM is cut out by the operation of relay#8. Relay #2 functions .as has already been described in connection withthe intercommunication between stations I and 2 Speakers LS and LS areconnected by depressing button P thereby closing the power circuitthrough relay #ll, cutting out the amplifier AM? and connecting thespeakers with the intercommunicating amplifier C as already described,through relays #3, #2 and #9.

The modified form of control employed in connection with the fixedwall-type panel as illustrated in connection with station CP preferablycomprises four switch contact disks E E E and E secured to a rotatablymounted shaft E so that they may be actuated as a gang. In a similarmanner, a two disk gang switch having contact disks E and E is provided,the same being mounted on shaft E All of the switches are shown in offposition. Switches E and E are for program selection, switches E and E7are for intercommunication control, and E designates a press-to-talkswitch.

Program selector disk E is provided with six contacts arranged to engageterminals of wires 26!], 2!, 202, 293, 204 and 205, the other terminalsof which are respectively connected with wires 60, 62, 64, 66, 68 and18. Disk E is also provided with six contacts arranged to engageterminals of wires 209 20W, 202 263 2M and 295 the other terminals ofwhich are connected with wires (ii, 63, 65, 6'5, 69 and- TI. Dummyresistors 206 similarto those shown on panel CP' may be provided.

Plate E which is the phonograph on and oif switch, contains six contactswhich are selectively brought into engagement with one terminal of awire 26'], the six contacts corresponding to the positions of said diskwhen rotated with shaft E The other terminal of wire 20'! is connectedwith wire 52! so as to be placed in circuit with the coil of relay #Ilwhereby the latter may be caused to function in the same manner asdescribed in connection with push button P Plate "E cooperates with thepower on-ofi switch E Said plate is provided with six contactscorresponding to the number of positions of the disk when rotated withdisks E and E so that at least one of a plurality leads 298 is at alltimes in engagement with a contact. Leads 298 are connected with a wire209 the other end of which is connected to wire I24 so as to control thecircuit to coil of relay #IS. Closing the circuit through any of theleads 2288 establishes a circuit from transformer D, wires 29, 28, coil#16, wires 125, I2 3, 289, switch E wires 2, 39, 438* to transformer D.Relay #16 closes circuit from program power supply A via wires 23,

21 contacts r, 8, wires 21, and 25 to return wire b. One terminal ofswitch E is connected with disk E by wire 2H], and said last mentionedwire is connected with wire 39 by means of a wire 2H. The other terminalof switch E is connected by a wire 212 with wirel IS. The operation ofswitch E is the same as that already described in connection with switchP.

Disks E and E are each provided with four active contacts correspondingto the number of stations in the system. The contacts of disk E arearranged to engage terminals of wires H5, H6, 2i"! and 2H8,respectively. The other ends of said wires are connected respectivelywith wires H7, H9, !22 and H3. The contacts of disk E are all connectedto leads 219 connecting with one terminal of the wire 220 the otherterminal of which is connected with wire I26. The circuits are the sameas heretofore described in connection with push buttons P F, P and P Theadvantages of the invention willcbe readily understood by those skilledin the art to which it appertains. For instance, it will be observedthat very simple and efiective means is provided for oralintercommunication between any two stations of a multistation receivingsystem without in any manner disturbing the normal functions of any ofthe other stations. A further advantage is that just as soon as thetemporary constructing and using the same, although without attemptingto set forth alloi the forms in which it may be made, or all of theforms of its use, what is claimed is:

l. A multiunit radio receiving system comprising a plurality ofreceiving units o-peratively connected with a radio receiving circuit,each unit including a sound reproducing device and its cir cuit, anintercommunication power circuit means commonto all of said receiving.units, means selectively controllable at each unit for "connecting thesound reproducing device of the same unit and the sound reproducingdevice of any other preselected unit with said intercommunication powercircuit, and means associated with each unit for changing the directionof current fiow through its sound reproducing device and-the preselectedsound reproducing device while'said devices are included in saidintercommunication power circuit. i

a 2. A multiunit radio receiving system. comprising a plurality ofreceiving unitsoperatively connected with a radio receiving circuit,each unit including a sound reproducing device and its circuit, anintercommunication power circuit means common to all of said receivingunits, means selectively controllable at each unit for disconnecting thesound reproducing device of that unit and of any other preselectedunitfrom their respective circuits, said means also including means forconnecting the said two sound reproducing devices with saidintercommunication power circuit simultaneously with the breaking of thesound-reproducing circuits, and means controllable at each station forreversing the direction of current flow through said two soundreproducing devices while the latter are connected with saidintercommunication power circuit.

3.. A multiunit radio receiving system comprising a plurality ofreceiving units operatively connected with a radio receiving crcuit,each unit including a sound reproducing device and its circuit, anintercommunication power circuit means common to all of said receivingunits, means selectively controllable at each unit for connecting thespeaker of the same unit and the speaker of any other preselected unitwith said intercommunication power circuit, means associated with eachunit for changing the direction of current flow through its sound.reproducing device as wellas the sound-reproducing device of thepreselected unit, while they are included in said intercommunicationpower circuit, and

means .for connecting said intercommunication power circuit with asource of electrical energy simultaneously with the interruption of the.normal current flow through the sound reproducing devices.

4'. A multiunit radio receiving system, comprising a plurality ofreceiving units operatively connected with a radio receiving circuit,eachunit including a sound reproducing device and its circuit and aplurality of program-selection'devices,:.10 means for controlling thevolume of selected program reproduction, an intercommunicationpowercircuit means common to all ofsaid receiving units, control meansassociated with each unit for disconnecting the sound reproducingdeviceof the same unit as well as the sound reproducing device of anyother preselected unit from the program selection means, meanscontrollable at each unit for connecting the sound reproducing device ofthe same unit and the sound I'GPI'OdUC-gfio ing device of thepreselected unit with said intercommunication power circuit, and meansassociated with each unitforv changing the direction of current fiowthrough the sound reproducing devices while the latter are included insaid inter-.7 5 communication power circuit.

5. A multiunit radio receiving system comprising a plurality of.receiving units operatively connected with a radio receiving circuit,means providing a normal amplifier circuit for each unit ao a soundreproducing'device associated with each unit and included in the normalamplifier circuit of thesame unit, an intercommunication power circuitmeans common to all of said receiving units, means providing" anintercommunication 3-5 amplifier circuit connected with saidintercommunication power circuit and also connected with the severalnormal amplifiercircuits of. the respective units, means selectivelycontrollable at each unit for disconnecting. the sound reproducing .40device of the same unit from its normal amplifier circuit and alsodisconnecting the sound repro-- ducing device of any other; preselectedunit from its normal amplifier circuit, said selective means alsoincluding means for connecting said disconnected sound reproducingdevices-with said intercommunication amplifier circuit, and meansassociated with each unitfor changing the direction of current flowthrough its sound reproducing device and the preselected'soundreproducing device while said devices are included in said'intercommunication amplifier circuit.

6. A multiunit radio receiving system comprising a plurality ofreceiving unitsoperatively connected with a radio receiving circuit,means pro- ,5 5

viding a normal amplifier circuit for eachunit, a

sound. reproducing device associated with each unit and included in thenormal amplifier circuit of the same unit, an intercommunicationamplifier circuit means common to all of said receiving units, means forbreaking each of said normal amplifier circuits, means for connectingeach sound reproducing device to thcintercommunication amplifying,circuit, means at each circuit for controlling the circuit breakingmeans 5 of its amplifier circuit and the connecting means of the soundreproducing device of any other preselected unitwith saidintercommunication amplifier circuit, and means associated with eachunit for changing the direction of current fiow 7 0 through thesoundreproducing device of the same unit and also through thepreselected sound reproducing devicewhile said devices are included insaid intercommunication amplifier circuit. {7 5 7. A multiunit radioreceiving system comprising a plurality of receiving units operativelyconnected with a radio receiving circuit, means providing a normalamplifier circuit for each unit, a sound reproducing device associatedwith each unit and included in the normal amplifier circuit of the sameunit, an intercommunication amplifier circuit means common to all ofsaid receiving units, means for breaking each of said normal amplifiercircuits, means for connecting each sound reproducing device to theintercommunication amplifier circuit, means for connecting saidintercommunication amplifier circuit with a source of current supply,means at each unit for controlling the circuit breaking means oi. itsamplifier circuit and for controlling the connecting means of the soundreproducing device of any other preselected unit with saidintercommunication amplifier circuit, and also for controlling the meansfor connecting the intercommunication amplifier circuit with said sourceof current supply, and means associated with each unit for changing thedirection of current flow through the sound reproducing device of thesame unit and also through the sound reproducing device of anypreselected unit while said devices are included in saidintercommunication amplifier circuit.

8. A multiunit radio receiving system comprising a plurality ofreceiving units operatively connected with a radio receiving circuit,each unit including a sound reproducing device and its circuit, anintercommunication power circuit means common to all of said receivingunits, means at each unit for breaking the circuits of the soundreproducing device of the same unit, and also for breaking the soundreproducer circuit of the sound reproducing device of. any otherpreselected unit, means for connecting the disabled sound reproducingdevices with said intercommunication power circuit, a common controlmeans associated with each unit for simultaneously actuating the meansfor breaking the said sound reproducer circuits and the means forconnecting the disabled sound reproducing devices with theintercommunication power circuit, and means associated with each unitfor changing the current flow through the sound reproducing device ofthe same unit while the previously disabled sound reproducers areconnected With said intercommunication power circuit.

9. A multiunit radio receiving system comprising a plurality ofreceiving units operatively connected with a radio receiving circuit,each unit including a sound reproducing device and its circuit, anintercommunication power circuit means common to all of said receivingunits, a relay controlling said intercommunication power circuit, saidrelay having reversing contacts, means associated with each unit forbreaking the first mentioned sound reproducer circuit of said unit,means associated with each unit for connecting one terminal of its soundreproducing device with said relay, means at each unit for actuating thecircuit breaking means of the sound reproducer circuit of the same unitand the sound reproducer circuit of any other preselected unit, andmeans associated with each unit for energizing said relay so as toreverse the normal fiow of the current through said intercommunicationpower circuit and the sound reproducing devices connected therewith.

10. A multiunit radio receiving system comprising a plurality ofreceiving units operatively connected with a radio receiving circuit,each unit including a normal amplifier circuit and a sound reproducingdevice in said circuit, an intercommunication amplifier circuit meanscommon to all of said receiving units, a relay having reversing contactsconnected with said intercommunication amplifier circuit, a circuitbreaker connected with one terminal of each sound reproducer circuit andalso connected with said relay, means associated with each unit foractuating the circuit breaker in the circuit of the loud speaker of thesame unit and also for operating the circuit breaker in the circuit ofthe loud speaker at any other preselected unit, and means associatedwith each unit for energizing said relay, so as to selectively reversethe current fiow through said sound reproducing devices while they areconnected with said intercommunication amplifier circuit.

11. A multiunit radio receiving system comprising a plurality ofreceiving units operatively connected with the radio input circuit, anamplifier circuit for each unit including a normally closed circuitbreaker, a sound reproducing device for each unit including a circuithaving a normally closed circuit breaker connected with one of itsterminals, an intercommunicating power circuit means common to all ofsaid receiving units, an intercommunication amplifier connected with thefirst mentioned amplifier circuits and also with said intercommunicationpower circuit, a reversing relay connected with said intercommunicationamplifying circuit, means connecting said reversing relay with thecircuit of each sound reproducing devices, means associated with eachunit for operating the first mentioned normally closed contacts to breakthe circuit to the sound reproducingdevice of the same unit, to breakcircuit to the sound reproducing device of any other preselected unit,and also to break the amplifier circuit of said preselected unit, andcontrol means associated with each unit for actuating said reversingrelay, whereby the flow of current through the sound reproducing devicesmay be reversed while said devices are connected with saidintercommunication power circuit.

12. A multiunit radio receiving system comprising a plurality ofreceiving units operatively connected with a common radio input circuit,each unit including a reproducing device and its operating circuit, avolume control circuit for each unit, normally closed contacts connectedwith one of the terminals of each of said sound reproducing devices, anintercommunication amplifier circuit means common to all of saidreceiving units, normally closed contacts in each of said soundreproducer circuits, a reversing relay having reversing contactsconnected with the intercommunication amplifier circuit, means forconnecting said relay contacts with a terminal of each of the soundreproducing devices, means for operating the circuit breakers to breakthe circuit to the sound reproducing device of said unit and to connectthe same with said relay, and also to selectively break the circuits tothe sound reproducing device of any other preselected unit,

terminals connected with a sound reproducing circuit, a volume controlcircuit for each unit, a pair of relays associated with each unit, oneof said relays of each unit being so connected with a terminal of thesound reproducing device of the same unit as to normally maintain aclosed circuit to the latter, the other of said relays being connectedwith the volume control circuit of the same unit, an intercommunicationamplifier circuit means common to all of said receiving units,

a relay having reversing contacts connected with said intercommunicationamplifier circuits, means connecting the contacts of said relay with thecontacts of each of said pairs of relays, so as to break the normalcircuit to the affected sound reproducing device of that unit and alsoto break the normal volume control circuit of the preselected unit, andto establish circuit connections with the intercommunication amplifiercircuit, and means associated with each unit for actuating the reversingrelay of the intercommunication amplifier circuit, whereby flow ofcurrent through the sound reproducing device of a unit may becontrollably reversed.

14. A multiunit radio receiving system comprising a plurality of.receiving units operatively connected with a common radio input circuit,a sound reproducing device for each unit having terminals connected witha sound reproducing circuit, a volume control circuit for each unit, areversing relay, a set of relays for each unit, one being a speakercontrol relay and the other a control relay, said last mentioned relayseach having two fixed contacts and one movable contact, the movablecontact of the speaker control relay being connected with one terminalof the sound reproducer circuit of the same unit, one of the fixedcontacts of the speaker control relay being connected with the movablecontact of the volume control relay, the other fixed contact of thespeaker control relay being connected with a terminal of the reversingrelay, one fixed contact of the volume control relay beim connected tothe opposite side of said reversing relay, and the other fixed contactof the volume control relay being connected with the volume controlcircuit of the same relay, a single operating device at each unit havingmeans controlling the circuits to the speaker control relay of the sameunit and the volume control relay of any other preselected unit, so asto break the speaker control and volume control circuits of the two lastmentioned relays and to place them in circuit with the reversing relay,and means associated with each unit for energizing said reversing relaywhereby flow of current through the previously disabled soundreproducing devices may be controllably reversed.

15. In a multistation system, a plurality of program-selector units,means selectively controlled at each station for operatively connectingthe station with any one of said program selector units, while theselected unit is operatively connected with any or all of the otherstations, and in such manner that the sound-volume-producing-functionsof said selected unit remain practically unimpaired irrespective of thenumber of stations connected therewith.

16. In a multistation system, a plurality of program-selector units, aplurality of operating circuits for the respective units there being onecircuit for each unit, a'plurality of circuit closers at each stationselectively controlling all of said circuits, said circuits and'theircircuit closers being so arranged that any one of the programselectorunits may be selectively connected with any station while the selectedunit is operatively connected with any one or' all of the otherstations, and in such manner that the sound-volume-producing-functionsof the selected unit remain practically unimpaired irrespective of thenumber of stations connected therewith.

17. In a multistation system, a plurality of program-selector units,means selectively controlled at each station for operativeiy connectingthe station with any one of said program selector units, while theselected unit is operatively connected with any or all of the otherstations, and in such manner that the sound reproduction functions ofthe various stations remain prac tically unimpaired irrespective of thenumber of stations connected therewith.

18. In a multistation system, a sound-reproducing element at eachstation, a plurality of program selection units, selective means at eachstation for operatively connecting the sound reproducing element withany one of said program selection units while said unit is operativelyconnected with any or all of the other stations, and

, in such manner that the sound-volume-produoing functions of theselected unit remain practically unimpaired irrespective of the numberof stations connected-therewith. l

19. In a multistation system, a sound-reproducing element at eachstation, a plurality of program selection units, selective means at eachstation for operatively connecting the sound reproducing element withany one of said program selection units while said unit is operativelyconnected with any or all of the other stations, and in such manner thatthesound-volume-producing functions of the various sta ions remainpractically unimpaired irrespective of the number of stations connectedtherewith.

RAYMOND KIMBALL.

